(1) Field of the Invention
The present invention relates to a pad for a steering wheel for a vehicle equipped with an air bag device and, more particularly, to a pad comprising a membrane switch forming member and a cover member for covering the air bag.
(2) Description of Related Art
A pad for a steering wheel including a membrane switch forming member and a cover member for covering the air bag, is disclosed in U.S. Pat. No. 5,062,661.
In this pad, the membrane switch forming member is arranged on a back face of a diaphragm of the cover member. The membrane switch forming member is composed of a conductive thin metal sheet and a rigid conductive thick metal sheet. An insulating foamed member is interposed between the two sheets.
When the switch forming member is actuated, the diaphragm of the cover member is pushed. Then, the foamed member is compressed so that the thin metal sheet is deformed to contact with the thick metal sheet, energizing the horn.
The reason why the switch forming member has to be made of rigid material will be described below. Specifically, the pad covers the folded air bag of the air bag device. As a result, the folded air bag biases the pad. Thus, without the rigid member, the switch might be always turned ON by the intense bias of the air bag.
However, the switch forming member of the U.S. Pat. No. 5,062,661 is heavy because it is arranged with the thick metal sheet. As a result, the cover member has its opening speed lowered by the weight of the switch forming member, when it is opened as the air bag is inflated.